Apparatus for producing ground and polished glass strip



Oct. 17, 1939. B WALDRQN AL 2,176,481

APPARATUS FOR PRODUCING GROUND AND POLISHED GLASS STRIP Original FiledMarch 4, 1958 2 Sheets-Sheet 1 Mmvrwm F. B. WALDRON El AL Oct. 17, 1939.

APPARATUSFOR PRODUCING GROUND AND POLISHED GLASS STRIP Original FiledMarch 4, 1938 2 SheetsSheet 2 hwmrwrs Patented Oct. 17, 1939 UNITEDSTATES PATENT OFFICE APPARATUS FOR PRODUCING GROUND AND POLISHED GLASSSTRIP Liability Acts Application March 4, 1938, Serial No. 193,908

Renewed August 10, March 10, 1937 4 Claims.

This invention relates to the simultaneous grinding and polishing ofboth sides of a continuous strip of glass, and has for its object animproved method and apparatus for maintaining the grinding and polishingtools central relatively to the strip.

In the type of apparatus to which the invention relates, the rotarygrinding tools are provided with grooves through which the abrasivepasses from the centre towards the periphery, but the periphery isformed with a continuous ring which is in contact throughout with theglass; this peripheral ring prevents the rapid escape of the abrasiveunder the action of centrifugal force.

Now it has been found impracticable to produce a continuous strip ofglass so straight laterally, that, while driven through the grinding andpolishing apparatus (constituted bya large number of grinding andpolishing tools operating on the upper and under surfaces of the strip),it remains central relatively to the tools. If the strip, at any point,deviates from the central position by more than a certain amount, theabovementioned peripheral ring reaches beyond the edge of the strip onone side, and there is then nothing to prevent the abrasive in thegrooves from being thrown outwardly from them. The result is that thetool is insufliciently provided with abrasive and ceases to operateeffectively.

In the case of polishing tools, which consist usually of felt covereddiscs rotatably mounted at a plurality of points on a rotating frame,the outermost discs have to overlap the edges of the strip in order thateffective polishing may be obtained. If, however, the overlap exceeds acertain amount the surfaces of the discs become injured by the edges ofthe glass and are no longer in the condition in which they produceeffective polishing.

If, therefore, the strip deviates from its central position by more thana certain amount, the discs overlap the edges insufficiently at one sideand too much at the other, and are in consequence injured.

In our co-pending application for Letters Patent of even date herewithwe have described a device whereby, when the strip deviates from itscentral position force is applied to it to bring it back to its centralposition. This device has been found effective so long as the deviationsof the strip are small, but, in practice, the deviations are such that,if sufficient force is applied to the strip to bring it central, it isliable to break.

According to the invention, the tools are car- 1939. In Great Britainried on frames which are adapted to slide transversely of the strip, andmeans are provided for slidably moving the said frames, so that the twotools of a pair of tools are moved simultaneously and equally,transversely of the strip. Pref- 5 erably, the frames are moved by amotor and a, switch is operated directly or indirectly by a transversemovement of the strip, and a hunting gear is provided to operate themotor to move the said frames in the same direction as the movement ofthe strip and by approximately the same amount.

In the accompanying drawings:

Figure 1 is a plan View of one grinding tool of a grinding apparatus,with its accompanying framework;

Figure 2 is a vertical section thereof along the line A-A of Figure 1;

Figure 3 is a view from the left hand side of Figure 1; and

Figure 4 is a diagrammatic view of a step by step switch circuit.

The strip of glass l is driven through the apparatus by pairs of rollersnot shown. It is ground between pairs of grinding tools 2, of whichthere are fifteen to twenty, and these are followed by a larger numberof polishing tools, when the strip is polished in the same apparatus.The shafts 3 of the tools are rotated (by means not shown) in bearingblocks 4, which are adapted to slide in frames 5. Means, not shown, areprovided for raising and lowering the tools in the frames 5. The frames5 rest on rectangular frames 6, and the lower frames 5 on rectangularframes 1.

The supporting framework of the apparatus consists of vertical boxcolumns 8 which support transverse box girders 9 and longitudinal boxgirders ID. The girders I 0 which continue to the left of Figure l areomitted. The transverse girders 9 carry slides II on which therectangular frames 6 rest and can slide, and slides l2 are fixed to thelower ends of the column 8 on which the rectangular frames 1 rest andcan slide. The tools 2 can therefore be moved transversely of the stripof glass I by the sliding of the frames 6 and I on the slides II and I2.

The means for moving the tools transversely are as follows: Two nuts 13are fixed to the frame 6, one near each end, and two nuts M- to theframe 1. Screws l5 and I6 engage the nuts l3 and I4 respectively andcarry bevel wheels l1 and I8 respectively. The two bevel wheels I! areconnected together by bevel wheels IS on a shaft 20 in the longitudinalgirder ID. The shaft 20 also carries bevel wheels 2| which engage bevel55 wheels 22 on two vertical shafts 23 in the columns 6. The verticalshafts 23 carry at their lower ends bevel wheels 24 which drive thebevel wheels I 8 on the screws l6 through bevel wheels and a shaftsimilar to the bevel wheels 2| and I9 and shaft 26. By theabove-described gearing, the four screws l5 and I 6 are turnedsimultaneously on turning the shaft 20, and thereby the frames 6 and 1,carrying the tools 2, are moved transversely together, and always remaincoaxial.

The screws may be turned by a hand wheel geared to the shaft 20, butpreferably they are turned by a motor connected to an automatic device.The motor 25 turns a worm wheel 26 on a shaft 21 which carries a bevelwheel 28 engaging the bevel wheel l9. When the edges of the strip arecut before the strip enters the grinding apparatus, the location of thestrip is conveniently ascertained by one edge of it, and Figures 1 to 3show a device whereby the motor 25 is turned in one direction or theother so as to maintain the axis of the tools 2 always at a fixeddistance from one edge of the strip. Thereby, when the strip is cut toconstant width, the axis of the tools may be maintained over the centreline of the strip whatever may be the position of the strip in atransverse direction.

A roller 29 (Figures 2 and 3) on the arm 30 of a lever pivoted at 3| toa bracket 32, is pressed against the edge of the strips l by a spring 33attached to the other arm 34 of the lever. The arm 34 is connected by alink 35 to the arm 36 of a lever pivoted at 31. The other arm 38 of thislever is forked to engage the arm 39 of a relay reversing switch 40 soconnected to the motor 25 that a movement of the arm 39 in one or theother direction causes the motor 25 to turn in one or the otherdirection.

In operation, if the strip l moves to the right (as seen in Figure 3)pressing the roller 29 to the right, the forked arm 38 moves to theright; this moves the arm 39 of the switch 46 to the right, closing themotor circuit to turn the motor so that the screws l5 and I6 turnrighthandedly. Thereby, the frames 6 and I are moved to the right, and,since the frame 6 carries the switch 40, this also moves to the rightuntil the arm 39 breaks the motor circuit. In this way. the tools 2carried by the frames 6 and I are caused to follow the transversemovement of the strip. The arm 39 is conveniently given play in the forkof the arm 38, so that small unimportant movements of the strip canoccur without causing movement of the tools. The above is one form ofthe device commonly termed a hunting gear, in which one member is causedto follow any movement of another member. Another form is showndiagrammatically in Figure 4, in which 4| and 42 are switch arms turnedby movement of the strip and of the tool frame respectively. Each switcharm has a series of contacts, such as a, b, c, A, B, C, connected asshown, and the two arms are connected to the mains through the armature43 of the motor 25. In the position shown, the circuit is open; if thestrip moves to turn the arm 4| to contact B, the circuit is closed, andthe motor turns to move the tool frame, and the arm 42 to contact 12,when the circuit is broken.

Similarly, a further movement of arm 4| to contact C closes the circuitwhich is opened again when arm 42 is moved to contact 0. The arm 42follows the arm 4| also in the other direction, provided that the motoris reversed. This is effected as follows: a second arm 44 is mountedfriction-tight on the spindle of the arm 4| and is adapted to makecontact with one of the two contacts 45 which are connected as shown tothe relay coils 46 of a reversing switch 41, adapted to reverse thecurrent through the shunt 48 of the motor. From the position shown, amovement to the left of the switch arm 4| carries with it the arm 44, tomake contact with the left hand contact 45, to reverse the motor shuntfield. The arm 44 remains in this position during any subsequentmovement of the arm 4| in the same direction, but reverses the motorfield on a reverse movement of the arm 4|.

In our above-mentioned co-pending application for Letters Patent,devices are described which are adapted to ascertain the location of thestrip with reference to its centre line, when the edges of the strip arenot cut, and cannot, therefore, be used to determine the location of thestrip. Any such device, which moves correspondingly to the centre lineof the strip, may be used to move the switch arm 4|, or the appropriatepart of any other hunting gear, instead of the roller 29 hearing againstthe edge of the strip.

Having described our invention, we declare that what we claim and desireto secure by Letters Patent is:

1. Apparatus for operating on a continuous strip of glass which ispassed longitudinally through the apparatus, comprising a plurality ofpairs of tools operating simultaneously on the upper and lower surfacesof the strip, with the two tools of each pair opposite one another,frames adapted to carry the tools and supports above the strip for theframes of the tools operating on the upper surface and supports belowthe strip for the frames of the tools operating on the lower surface,slideways on the supports transversely of the apparatus on which theframes are adapted to slide, means for holding the frames on theslideways in a predetermined operative transverse position relatively tothe supports and to the strip, and means, operable when the strip movestransversely, for moving the frames to an operative position which isdifferent relatively to the supports but substantially the samerelatively to the strip.

2. Apparatus for operating on a continuous strip of glass which ispassed longitudinally through the apparatus, comprising a plurality ofpairs of tools operating simultaneously on the upper and lower surfacesof the strip, with the two tools of each pair opposite one another,frames adapted to carry the tools and supports above the strip for theframes of the tools operating on the upper surface and supports belowthe strip for the frames of the tools operating on the lower surface.slideways on the supports a transversely of the apparatus on which theframes are adapted to slide, means for holding the frames on theslideways in a predetermined operative transverse position relatively tothe supports and to the strip, and means, set into operation by alateral movement of the strip, for moving the frames to an operativeposition which is different relatively to the supports but substantiallythe same relatively to the strip.

3. Apparatus for operating on a continuous strip of glass comprising aplurality of pairs of tools operating simultaneously on the upper andlower surfaces of the strip, with the two tools of each pair oppositeone another, frames adapted to carry the tools and supports above thestrip for the frames of the tools operating on the upper surface andsupports below the strip for the frames of the tools operatingvon thelower surface, slideways on the supports transversely of the strip onwhich the frames are adapted to slide, a motor connected by gearing withthe two frames carrying the tools of a pair, a switch operated when thestrip makes a transverse movement and a hunting gear comprising the saidswitch adapted to operate the motor to move the said frames in the samedirection as the movement of the strip and by approximately the sameamount.

4. In a glass grinding apparatus including a plurality of grinding toolsarranged to operate simultaneously on both surfaces of a continuousstrip of glass passing through the apparatus, the combination of meansfor shifting the grinding tools laterally, relatively to the strip tomaintain the strip and grinding tools in centralized relation during thegrinding period, and automatic means for controlling the operation ofsaid shifting means to correct for any deviation from said centralizedrelation.

FREDERIC BARNES WALDRON.

FRANK EDWIN SIDCOMBE.

